Hi.  I've just joined, so apologies for not being timely.  I have been exploring some "natural" materials for use (mostly in  topical systems).  Of course it depends if you are trying to preserve against oxidation, or if you are looking for antimicrobial activity as well.  Vitamin E is great as an antioxidant, but doesn't do anything with regard to micro as far as I know--it's also challenging to formulate. 

For micro, sorbates and benzoates can work very well, although some molds seem to be able to evade their activity.  Benzoin and Vannilin have strong odors that might or might not suit your application.  You are right to be wary of benzoates from everything I hear, despite their long history of safe use.  I'm currently particularly interested in a biomolecule produced in kimchee fermentation.  A company called Active Micro Systems in Piscataway, NJ makes what they call AMS Leucidal Liquid, for which they have nice looking kill data below pH 9.  The material is used at about 2% and doesn't have any particular odor (which was a concern in my application).  Hope some of that might be useful.

Desiree are you looking for micro or oxidation in the beverage?

Hello all,  I've just joined so hope this info is helpful.   Regarding natural antimicrobials some of the organic acids such as lactic, salts (sodium lactate) and blends, acetic acid/lactic acid, and acetic acid and sodium lactate are effective.  There are natural ingredients from ferments on various media such as whey solids and corn solids. All of these are effective depending upon the application and pH.  Their use level is generally higher vs. the Benzoate and Sorbates, which are not natural and very dependent upon pH.  Let me know if you want brand names.

We (Univar USA) works very closely with our suppliers, Kerry and Purac being just two.  Kerry has a line of fermented antimicrobials; Upgrade for bakery effective against yeast and mold; Alta for meat and culinary effective against Listeria, yeast and mold; Perlac for meat and deli effective against lactic acid bacteria and spore formers.  Purace as Purac 88 lactic acid, Purasal sodium lactate, Purac Fresh S and Purac Fresh S39.  All of these are effective agains mold, yeast, bacteria, depending upon the pH and application.  I can request samples for you and get you in touch with our sales rep for pricing if interested.

Neutral pH is a tough one.  My focus is pretty much food which is mostly heat treated when over a pH of 5, or frozen.  Purasal is sodium lactate and effective up to a pH of 7.  Of course it is all trial and error and storage testing to determine efficacy.